Self calibrating camera device

ABSTRACT

An illustrative example camera device includes a substrate and a sensor supported on the substrate. The sensor is configured to gather image information. A lens is situated near the sensor and an electroactive polymer selectively causes relative movement between the sensor and the lens.

BACKGROUND

A variety of sensor types have proven useful for providing enhancedfeatures and control on automotive vehicles. Cameras are useful fordetecting objects nearby or in a pathway of a vehicle and providingvisual information to a driver. The types of cameras included onvehicles typically require that the lens and sensor be aligned withextreme precision. Known techniques to achieve such alignment rely onexpensive equipment and introduce complexity and delays into themanufacturing process. For example, a five-axis machine controls therelative positions of the lens and sensor during active focuscalibration. Once the desired alignment is achieved, at least one curecycle secures the components in place.

Known camera assembly techniques have another drawback in addition tothe added expense associated with the specialized equipment and timedelays mentioned above. Once the camera sensor and lens are cured inposition, future adjustment or calibration is not possible. Given thewide range of environmental conditions vehicles and their components areexposed to over time, camera devices are subject to material creep,printed circuit board warping, stresses from mechanical shock andvibration, and deterioration of the adhesive that secures the lens andsensor in the calibrated position. It is not possible to adjust orrecalibrate the camera over time, which introduces additional expensesif a camera is replaced. If not replaced, the camera simply remains in aless-than-ideal calibration state.

SUMMARY

An illustrative example camera device includes a substrate and a sensorsupported on the substrate. The sensor is configured to gather imageinformation. A lens is situated near the sensor and an electroactivepolymer selectively causes relative movement between the sensor and thelens.

An example embodiment having one or more features of the camera deviceof the previous paragraph includes a controller that is configured tocontrol electrical energy applied to the electroactive polymer in anamount that causes the relative movement between the sensor and thelens.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the controller is configuredto determine when the camera device is in a calibrated state, determineat least one characteristic of the electrical energy applied to theelectroactive polymer when the camera device is in the calibrated state,and maintain the at least one characteristic of the electrical energy tomaintain the calibrated state of the camera device.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the controller is configuredto selectively adjust a position of at least one of the sensor or lensrelative to the other of the lens or sensor to recalibrate the cameradevice.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the electroactive polymer issituated against the substrate and the substrate includes at least oneconductive trace for providing electrical energy to the electroactivepolymer.

An example embodiment having one or more features of the camera deviceof any of the previous paragraphs includes a housing supporting the lensand the substrate. The electroactive polymer is situated between thesubstrate and a reaction surface of the housing, a space occupied by theelectroactive polymer changes responsive to electrical energy, theelectroactive polymer reacts against the reaction surface as the spaceoccupied by electroactive polymer changes, and a position of thesubstrate relative to the housing changes as the electroactive polymerreacts against the reaction surface.

An example embodiment having one or more features of the camera deviceof any of the previous paragraphs at least one resilient memberassociated with the substrate for allowing relative movement between thesubstrate and the reaction surface as the electroactive polymer reactsagainst the reaction surface.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the at least one resilientmember biases the substrate toward the reaction surface.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the electroactive polymercomprises a plurality of portions supported on the substrate and the atleast one resilient member comprises a plurality of members respectivelyassociated with the portions of the electroactive polymer.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the housing includes asubstrate support, at least one fastener is received through an openingin the substrate support, the at least one fastener is secured to thehousing, and the at least one resilient member is associated with the atleast one fastener and situated to allow relative movement between thesubstrate support and the reaction surface.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the lens is supported in afixed position relative to the housing.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the relative movement includesat least one of a change in a distance between the sensor and the lensand a change in an angle of tilt between the sensor and the lens.

In an example embodiment having one or more features of the cameradevice of any of the previous paragraphs, the electroactive polymercomprises a plurality of portions supported on the substrate inrespective locations, each of the portions responds to an amount ofelectrical energy applied to it, and different amounts of electricalenergy applied to the portions, respectively, causes different relativemovements between the sensor and the lens.

An illustrative example method of calibrating a camera device includesproviding electrical energy to an electroactive polymer to causerelative movement between a sensor and a lens of the camera device toachieve a first relative orientation between the sensor and the lens,obtaining a first camera image of a reference when the sensor and thelens are in the first relative orientation, determining whether acorrespondence between the first camera image and the referenceindicates that the camera device is calibrated.

In an example embodiment having one or more features of the method ofthe previous paragraph, the correspondence between the first cameraimage and the reference indicates that the camera device is notcalibrated and the method includes providing a different amount ofelectrical energy to the electroactive polymer to cause relativemovement between the sensor and the lens to achieve a second, differentrelative orientation between the sensor and the lens, obtaining a secondcamera image of a reference when the sensor and the lens are in thesecond relative orientation, and determining whether a correspondencebetween the second camera image and the reference indicates that thecamera device is calibrated.

In an example embodiment having one or more features of the method ofany of the previous paragraphs, the electroactive polymer comprises aplurality of portions and providing the electrical energy comprisesproviding electrical energy having a first characteristic to a first oneof the portions and providing electrical energy having a second,different characteristic to a second one of the portions.

In an example embodiment having one or more features of the method ofany of the previous paragraphs, the relative movement between the sensorand the lens changes at least one of a distance between the sensor andthe lens and an angle of the sensor relative to the lens.

In an example embodiment having one or more features of the method ofany of the previous paragraphs, the camera device is supported on avehicle and the method comprises performing the providing, obtaining anddetermining a plurality of times during a service life of the cameradevice.

An illustrative example camera device includes a substrate, sensor meanssupported on the substrate for gathering image information, a lens nearthe sensor, an electroactive polymer that selectively causes relativemovement between the sensor and the lens, and control means forcontrolling electrical energy applied to the electroactive polymer in anamount that causes the relative movement between the sensor and thelens.

In an example embodiment having one or more features of the cameradevice of the previous paragraph, the control means is configured toselectively adjust a position of at least one of the sensor or lensrelative to the other of the lens or sensor for recalibrating the cameradevice.

The various features and advantages of at least one disclosed exampleembodiment will become apparent to those skilled in the art from thefollowing detailed description. The drawings that accompany the detaileddescription can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 diagrammatically illustrates an example vehicle including atleast one camera designed according to an embodiment of this invention.

FIG. 2 diagrammatically illustrates selected an example camera device.

FIG. 3 is a cross-sectional illustration taken along the lines 3-3 inFIG. 2.

FIG. 4 schematically illustrates selected features of an example cameradevice.

FIG. 5 is a flowchart diagram summarizing a method of calibrating acamera device.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates camera devices 20 supported on avehicle 22. The camera devices 20 may be used for a variety of detectionor image gathering purposes, such as detecting objects or conditions ina vicinity of the vehicle.

As shown in FIGS. 2-4, the cameras 20 each include a housing 30 thatsupports a lens 32. A sensor 34 that is configured to capture images orgather image information is supported on a substrate 36. In theillustrated example embodiment, the substrate 36 is a generally planarprinted circuit board. The sensor 34 is secured in a fixed position onthe substrate 36, which is accomplished by soldering the sensor 34 inplace in some embodiments.

An electroactive polymer 40 responds to electrical energy by changingshape or volume. The electroactive polymer 40 selectively causesrelative movement between the sensor 34 and the lens 32 as it respondsto changes in electrical energy provided to it. Such relative movementis useful for focusing or calibrating the camera 20. One feature of theillustrated example embodiment is that the electroactive polymerfacilitates camera calibration during a manufacturing process andsubsequently as may be needed during the service life of the camera 20.This feature is different from many camera devices in which the lens andsensor are set in manner that does not allow subsequent adjustment oncethe device is made.

In the illustrated example embodiment, the electroactive polymer 40includes a plurality of portions or pads situated on the substrate 36.The portions of the electroactive polymer 40 are situated between thesubstrate 36 and a reaction surface 42 on the housing 30. The substrate36 is supported in the housing by a substrate support 44. A plurality offasteners 46, such as screws, hold the substrate support 44 in a desiredlocation within the housing 30. Resilient members 48 are associated withthe fasteners 46 and the substrate support 44 to allow for some movementof the substrate 36 within the housing. The resilient members 48comprise springs in some embodiments and compressive pads in otherembodiments. The resilient members 48 bias the substrate 36 and theportions of electroactive polymer 40 toward the reaction surface 42.

As shown in FIG. 4, the camera 20 includes a controller 50 thatselectively provides electrical energy to the portions of electroactivepolymer 40. In this example, circuit traces 52 on the substrate 36conduct the desired amount of electrical energy to the portions of theelectroactive polymer 40.

The controller 50 includes a processor or another computing device andmemory. The controller 50 selectively provides electrical energy to theportions of electroactive polymer 40, respectively, to achieve a desiredorientation between the lens 32 and the sensor 34. By changing theamount of electrical energy provided to each portion of electroactivepolymer, the controller 50 is able to cause relative movement betweenthe sensor 34 and the lens in three dimensions. For example,individually causing the portions of electroactive polymer 40 to expandor contract as schematically shown by the arrows 54 changes the positionof the corresponding portion of the substrate 36 relative to thereaction surface 42 of the housing 30. The sensor 34 moves with thesubstrate 36 and therefore the distance between the lens 32 and thesensor 34 is adjustable as schematically shown by the arrows 56 in FIG.4. Additionally, the controller 50 can control the electrical energyprovided to the pads or portions of electroactive polymer 40 toselectively adjust a tilt angle of the sensor 34 as schematically shownby the adjustment arrow 58.

Causing relative movement between the lens 32 and the sensor 34facilitates calibrating the camera 20. An example calibration techniqueis summarized in the flow chart 60 of FIG. 5. Calibration begins at 62.At 64, the sensor 34 obtains an image of a reference, such as a knownpattern or series of visible images. The controller 50 determineswhether the image obtained by the sensor 34 corresponds to the referenceat 66. If there is insufficient correspondence between the capturedimage information and the reference, the controller changes theelectrical energy provided to at least one of the portions ofelectroactive polymer 40 at 68. The sensor obtains another image at 64and the controller compares the most recently obtained image with thereference at 66. This process continues until there is sufficientcorrespondence between the captured image and the reference to indicatethat the camera is properly calibrated. Once calibrated, at 70, thecontroller 50 stores at least one characteristic of the electricalenergy provided to the respective portions of electroactive polymer 40.Example stored characteristics include voltage and current. The storedcharacteristics are subsequently used by the controller 50 to place orkeep the sensor 34 and the lens 32 properly aligned to maintaincalibration of the camera 20.

One feature of the illustrated embodiment is that it is possible toperform such calibration during a manufacturing process and subsequentlyat various times during the service life of the camera 20. For example,when the camera 20 is supported on the vehicle 22 it is possible fortemperature conditions or impact to adversely affect the components ofthe camera 20 causing the camera 20 to lose calibration or to operate ina less-than-ideal manner. When a suitable reference is available, suchas at a vehicle service center, the controller 50 can execute thecalibration process summarized above to recalibrate the camera 20.Previous camera configurations without the electroactive polymer 40could not be recalibrated because the lens 32 and sensor 34 are fixed ina manner that does not allow subsequent adjustment.

There are known electroactive polymer materials and those skilled in theart who have the benefit of this description will be able to select anappropriate material for their particular situation. An electroactivepolymer is considered advantageous over a piezoelectric material, forexample, because electroactive polymers have better strain percentageproperties allowing for more adjustment or relative movement between thelens 32 and the sensor 34.

Although the sensor 34 and substrate 36 are moveable relative to thehousing 30 while the lens remains stationary relative to the housing 30in the illustrated example embodiment, other embodiments include amoveable lens 32.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthe essence of this invention. The scope of legal protection given tothis invention can only be determined by studying the following claims.

1. A camera device, comprising: a substrate; a sensor disposed on afirst side of the substrate, the sensor being configured to gather imageinformation; a lens near the sensor; and an electroactive polymer thatselectively causes relative movement between the sensor and the lens,the electroactive polymer comprising a plurality of pads disposed on thefirst side of the substrate at locations distal from one another.
 2. Thecamera device of claim 1, comprising a controller that is configured tocontrol electrical energy applied to the electroactive polymer in anamount that causes the substrate and the sensor to move relative to thelens.
 3. The camera device of claim 2, wherein the controller isconfigured to: determine when the camera device is in a calibratedstate; determine at least one characteristic of the electrical energyapplied to the electroactive polymer when the camera device is in thecalibrated state; and maintain the at least one characteristic of theelectrical energy to maintain the calibrated state of the camera device.4. The camera device of claim 2, wherein the controller is configured toselectively adjust a position of at least one of the sensor or lensrelative to the other of the lens or sensor to recalibrate the cameradevice.
 5. The camera device of claim 1, wherein the electroactivepolymer is situated against the substrate; and the substrate includes atleast one conductive trace for providing electrical energy to theelectroactive polymer.
 6. The camera device of claim 1, comprising ahousing supporting the lens and the substrate, wherein: theelectroactive polymer is situated between the substrate and a reactionsurface of the housing that faces the first side of the substrate; aspace occupied by the electroactive polymer changes responsive toelectrical energy; the electroactive polymer reacts against the reactionsurface as the space occupied by electroactive polymer changes; and aposition of the substrate relative to the housing changes as theelectroactive polymer reacts against the reaction surface.
 7. The cameradevice of claim 6, comprising at least one resilient member associatedwith the substrate for allowing relative movement between the substrateand the reaction surface as the electroactive polymer reacts against thereaction surface.
 8. The camera device of claim 7, wherein the at leastone resilient member biases the substrate toward the reaction surface.9. The camera device of claim 7, wherein the at least one resilientmember comprises a plurality of members respectively associated with theplurality of pads of the electroactive polymer.
 10. The camera device ofclaim 7, wherein: the housing includes a substrate support that supportsthe substrate at support locations on a second side of the substratethat is opposite the first side; the support locations correspond to theplurality of pads of the electroactive polymer to cause the substrate tobias the plurality of pads of the electroactive polymer against thereaction surface of the housing; at least one fastener is receivedthrough an opening in the substrate support; the at least one fasteneris secured to the housing; and the at least one resilient member isassociated with the at least one fastener and situated to allow relativemovement between the substrate support and the reaction surface.
 11. Thecamera device of claim 6, wherein the lens is supported in a fixedposition relative to the housing.
 12. The camera device of claim 1,wherein the relative movement includes at least one of a change in adistance between the sensor and the lens and a change in an angle oftilt between the sensor and the lens.
 13. The camera device of claim 1,wherein: each of the plurality of pads of the electroactive polymerresponds to an amount of electrical energy applied to it; and differentamounts of electrical energy applied to respective pads of the pluralityof pads causes different relative movements between the sensor and thelens.
 14. A method of calibrating a camera device, the methodcomprising: providing electrical energy to an electroactive polymercomprising a plurality of pads disposed on a first side of a substrateat locations distal from one another to cause relative movement betweena sensor, disposed on the first side of the sensor, and a lens of thecamera device to achieve a first relative orientation between the sensorand the lens; obtaining a first camera image of a reference when thesensor and the lens are in the first relative orientation; anddetermining whether a correspondence between the first camera image andthe reference indicates that the camera device is calibrated.
 15. Themethod of claim 14, wherein: the correspondence between the first cameraimage and the reference indicates that the camera device is notcalibrated; and the method comprises: providing a different amount ofelectrical energy to the electroactive polymer to cause relativemovement between the sensor and the lens to achieve a second, differentrelative orientation between the sensor and the lens; obtaining a secondcamera image of a reference when the sensor and the lens are in thesecond relative orientation; and determining whether a correspondencebetween the second camera image and the reference indicates that thecamera device is calibrated.
 16. The method of claim 14, wherein:providing the electrical energy comprises providing electrical energyhaving a first characteristic to a first one of the plurality of padsand providing electrical energy having a second, differentcharacteristic to a second one of the plurality of pads.
 17. The methodof claim 14, wherein the relative movement between the sensor and thelens changes at least one of a distance between the sensor and the lensand an angle of the sensor relative to the lens.
 18. The method of claim14, wherein the camera device is supported on a vehicle and the methodcomprises performing the providing, obtaining and determining aplurality of times during a service life of the camera device.
 19. Acamera device, comprising: a substrate; sensor means disposed on a firstside of the substrate for gathering image information; a lens near thesensor; an electroactive polymer that includes a plurality of padsdisposed on the first side of the substrate at locations distal from oneanother and that selectively causes relative movement between the sensorand the lens; and control means for controlling electrical energyapplied to respective pads of the plurality of pads of the electroactivepolymer in an amount that causes the relative movement between thesensor and the lens.
 20. The camera device of claim 19, wherein thecontrol means is configured to selectively adjust a position of at leastone of the sensor or lens relative to the other of the lens or sensorfor recalibrating the camera device.